The production of conventional textile fabrics is known to be a complex, multi-step process. The production of fabrics from staple fibers begins with the carding process where the fibers are opened and aligned into a feedstock known as sliver. Several strands of sliver are then drawn multiple times on a drawing frames to further align the fibers, blend, improve uniformity as well as reduce the sliver's diameter. The drawn sliver is then fed into a roving frame to produce roving by further reducing its diameter as well as imparting a slight twist. The roving is then fed into the spinning frame where it is spun into yarn. The yarns are next placed onto a winder where they are transferred into larger packages. The yarn is then ready to be used to create a fabric.
For a woven fabric, the yarns are designated for specific use as warp or fill yarns. The fill yarns (which run on the y-axis and are known as picks) are taken straight to the loom for weaving. The warp yarns (which run on the x-axis and are known as ends) must be further processed. The large packages of yarns are placed onto a warper frame and are wound onto a section beam were they are aligned parallel to each other. The section beam is then fed into a slasher where a size is applied to the yarns to make them stiffer and more abrasion resistant, which is required to withstand the weaving process. The yarns are wound onto a loom beam as they exit the slasher, which is then mounted onto the back of the loom. The warp yarns are threaded through the heedels of the loom, which raises and lowers the individual yarns as the filling yarns are inserted perpendicular in an interlacing pattern thus weaving the yarns into a fabric. Once the fabric has been woven, it is necessary for it to go through a scouring process to remove the size from the warp yarns before it can be dyed or finished. Currently, commercial high speed looms operate at a speed of 1000 to 1500 picks per minute, where a pick is the insertion of the filling yarn across the entire width of the fabric. Sheeting and bedding fabrics are typically counts of 80×80 to 200×200, being the ends per inch and picks per inch, respectively. The speed of weaving is determined by how quickly the filling yarns are interlaced into the warp yarns, therefore looms creating bedding fabrics are generally capable of production speeds of 5 inches to 18.75 inches per minute.
In contrast, the production of nonwoven fabrics from staple fibers is known to be more efficient than traditional textile processes as the fabrics are produced directly from the carding process.
Nonwoven fabrics are suitable for use in a wide variety of applications where the efficiency with which the fabrics can be manufactured provides a significant economic advantage for these fabrics versus traditional textiles. However, nonwoven fabrics have commonly been disadvantaged when fabric properties are compared, particularly in terms of surface abrasion, pilling and durability in multiple-use applications. Hydroentangled fabrics have been developed with improved properties that are a result of the entanglement of the fibers or filaments in the fabric providing improved fabric integrity. Subsequent to entanglement, fabric durability can be further enhanced by the application of binder compositions and/or by thermal stabilization of the entangled fibrous matrix.
U.S. Pat. No. 3,485,706, to Evans, hereby incorporated by reference, discloses processes for effecting hydroentanglement of nonwoven fabrics. More recently, hydroentanglement techniques have been developed which impart images or patterns to the entangled fabric by effecting hydroentanglement on three-dimensional image transfer devices. Such three-dimensional image transfer devices are disclosed in U.S. Pat. No. 5,098,764, hereby incorporated by reference, with the use of such image transfer devices being desirable for providing a fabric with enhanced physical properties as well as an aesthetically pleasing appearance.
For specific applications, a nonwoven fabric must exhibit a combination of specific physical characteristics. For example, fabrics used in the home should be soft and drapeable, yet withstand home laundering, and be resistant to abrasion (which can result in fabric pilling). Fabrics used in the home must also exhibit sufficient strength and tear resistance, and colorfastness. These are among the characteristics which have been identified as being desirable for so-called “top-of-the-bed” applications, such as comforters, pillows, dust ruffles, and the like.
Heretofore, attempts have been made to develop nonwoven fabrics exhibiting the necessary aesthetic and physical properties through the use of specialized lyocell fibers. Lyocell is a natural cellulosic fiber spun from an amine oxide solvent developed by American ENKA, Asheville, N.C. in the late 1970's. U.S. Pat. No. 6,210,801, and U.S. Pat. No. 6,235,392, incorporated herein by reference, detail useful cellulosic compositions and the method of spinning such lyocell fibers. Courtaulds Fibers Inc. of Axis, Ala. (“Courtaulds”) markets lyocell fiber under the brand name of TENCEL in lengths suitable for short-staple and worsted and woolen spinning systems. TENCEL fibers has a highly crystalline structure and is fabricated from an amine oxide solvent of N-methylmorpholine N-oxide, commonly referred to as NMMO. The industry has found that TENCEL materials are superior to other cellulosics, including cotton and rayon in tensile and aesthetic properties which make it suitable for use in the textile field.
Various attempts have been made to fabricate lyocell fabrics with enhanced physical properties. Published Japanese Patent Application No. 10037059, discloses a method of forming a lyocell-based fabric comprising a lyocell filament yarn, whereby fibrillation of the lyocell under high pressure acts to interlace the yarn into a web construction. Published PCT Applications No. 98/26122 and 99/64649, are directed to a continuous extrusion process whereby lyocell filaments are formed and collected as a fiber web. U.S. Pat. No. 5,870,807, incorporated herein by reference, teaches to a “hydroenhancement” procedure whereby a pre-existing woven lyocell fabric is subjected to wet-processing and enzymatic hydrolysis treatments.
Notwithstanding various attempts in the prior art to develop a nonwoven fabric acceptable for home use applications, a need continues to exist for a nonwoven fabric which provides the desired softness and drapeability, as well as the requisite mechanical characteristics.